(1) Field of the Invention
This invention relates to food compositions containing barley and, more particularly, to food compositions comprising proanthocyanidin-free barley and iron. The iron-fortified composition is organoleptically acceptable and does not possess the grayish color typical of iron-fortified barley compositions.
(2) Description of the Related Art
Iron deficiency continues to be a significant world health problem in both developing and industrialized countries. Particularly affecting are infants, toddlers, pregnant women, and menstruating women (see DeMaeyer et al. in Iron Fortification of Foods, Clydesdale and Wiemer, Eds, Academic Press, 1985, pp. xi-xii; Beard et al. in Iron Fortification of Foods, Clydesdale and Wiemer, Eds, Academic Press, 1985, pp. 3-16). Fortification of foods with iron can be an effective means of avoiding or overcoming iron deficiency (Hurrell, Nutrition Rev. 55:210-222, 1997). Cereal-based foods are the most commonly used vehicles for fortification with iron because of their stability as a carrier for nutrients and their broad usage (Proposed Fortification Policy for Cereal-Grain Products, National Research Council, Food and Nutrition Board, 1974).
Infants are particularly susceptible to iron deficiency because of their rapid growth rate and the relatively low iron content of most foods that have not been fortified. As a result, iron deficiency is the most prevalent nutritional deficiency among infants and young children (Ziegler, et al, Nutrition Rev. 54:348-354, 1996). The fortification of infant formulas and cereals has been advocated as a strategy for preventing iron deficiency in infants (Id.).
One problem often associated with the addition of iron to food products has been the development of undesirable organoleptic qualities of the food due to unacceptable changes in color and flavor (Hurrell, Nutrition Rev 55:210-222, 1997). For example, ferrous fumarate has been studied for its possible use in fortifying chocolate milk drinks, however, the powdered chocolate milk product turned an unattractive gray color when reconstituted with boiling water or boiling milk (Hurrel et al., British J. Nutrition 65:271-283, 1991). Similar undesirable color changes can occur in infant cereals when the cereal is made into a pap with milk or water (Hurrell et al. Am J. Clin Nutr 49:1274-1282, 1989).
Phenolic compounds in infant cereals have been implicated in the color changes resulting from the addition of iron compounds (Hurrell, 1997, supra). It has been reported that Ferrous sulfate can react with phenolic compounds to form blue-black colors and darken food products containing large amounts of tannin, like chocolate and barley flour (Barrett et al. in Iron Fortification of Foods, Clydesdale and Wiemer, Eds, Academic Press, 1985, pp. 75-109 citing Waddel, The Bioavailability of Iron Sources and their Utilization in Food Enrichment, FASEB Report for the FDA, Bethesda, Md., 1973). Nevertheless, these earlier works did not identify any particular compounds responsible for the discoloration of food products upon addition of iron. Indeed, phenolic compounds, of which the group of compounds referred to as tannins have been considered one type, constitute a wide range of compounds (Bravo, Nutrition Rev. 56:317-333, 1998).
Currently, one of the more popular commercial instant infant cereals is barley Cereal. barley, however, is unique among the common cereal grains of North America in that it is especially rich in polyphenolic compounds, including tannins (Bravo, 1998, supra). Barley is reported to contain 1200 to 1500 mg total polyphenols per 100 grams of dry weight, compared to 22 to 40 mg for wheat, 30.9 mg for corn, 8.7 mg for oats and 8.6 mg for rice (Id.). As a result, barley cereal made with electrolytic iron, which is commonly used to fortify instant infant cereals (Ziegler et al., 1996, supra), has a tendency to turn gray during manufacture and during reconstitution by the consumer unless the electrolytic iron is encapsulated in a water-insoluble matrix (see example 1 below).
One approach to avoiding the iron discoloration of food products has been to adjust the pH of the food product to an acidic value. Mehansho et al. (U.S. Pat. No. 5,670,344) reported that the development of gray color in a chocolate drink product upon reconstitution with water or milk, is prevented by buffering the chocolate drink product to a pH of 6.5 or less. Cereal-based foods made with barley, however, do not react in the same manner as chocolate and adjusting the pH of a barley flour mixture with added iron, does not prevent the graying of the composition at acceptable levels of acidity (see example 2 below).
Thus, it would be desirable to devise a workable approach for fortifying barley-containing food products with iron without the development of a an organoleptically unacceptable discoloration of the food product.